Parasites of the predator, Liasis fuscus, and its prey, Rattus colletti, on the Adelaide River floodplain, Northern Territory, Australia

A comprehensive survey of the parasites of the water python, Liasis fuscus, and the dusky rat, Rattus colletti, on the Adelaide River floodplain, Northern Territory, Australia, was undertaken. Sampling of sympatric hosts was also undertaken, however only six water rats, Hydromys chrysogaster, were collected. Influences of seasonal and host ecology on parasite community structure was then examined.

The L. fuscus and R. colletti populations were sampled six times each, encompassing three wet seasons and three dry seasons. Endoparasites, ectoparasites, blood smears, faecal and tissue samples were collected. Ten species of endoparasite, namely the nematodes Dracunculus mulbus, Dioctowittus hughjonesi, Ophidascaris robertsi, Pseudabbreviata sp., Pseudostrongyluris polychrus, Eustrongylides acrochordus, the cestode Bothridium pithonis and Bothridium ornatum, diphyllobothriid spargana, and the pentastome Raillietiella sp. were collected from L. fuscus. Two ectoparasite species, Aponomma fimbriatum and Amblyomma limbatum were also collected. Faecal egg counts revealed cestode eggs but no protozoa were found in faecal or tissue samples. The intra-erythocytic protozoan Hepatozoon sp. was found in blood smears.

Six species of endoparasite, namely the nematodes Nippostrongylus typicus, Mastophorus muris and Peramelistrongylus sp., the cestodes Hymenolepis diminuta and Raillietina celebensis and the trematode Echinoparyphium hydromyos were recorded from R. colletti. Four ectoparasite species, Haemaphysalis ratti, Peramelaelaps bandicoota, Hoplopleura sp. and fleas from the family Pulicidae were also found. No helminth eggs or protozoan oocysts were found in faecal samples, nor protozoa in tissue or blood samples.

From the six water rats collected, three endoparasite species, Uncinaria hydromyidis, Hymenolepis australiensis and Echinoparyphium hydromyos, were recovered. The protozoan Klossiella sp. was found in kidney tubules.

The parasite community within L. fuscus was found to be an isolationist community of endoparasites, characterised by low colonising ability, reproductive isolation, small population sizes and vacant niches, in combination with an 'insulating' effect from seasonal changes in community structure caused by the specialised diet of L. fuscus.

In the parasite community of R. colletti, seasonal influences appear to be reducing the survival and maintenance of parasite populations producing a depauperate community, mainly caused by the annual habitat shift, unlike that found in other Australian species of Rattus species.